Combined focus and centering control for cathode ray tubes



Sept. 5, '1950 G J HExslG 2,521,061

COMBINED Focus 'ANO CENTERING CONTROL FOR cATHoDE-RAY TUBES Filed March 18, 194e IN V EN TOR.

rent power supply generally designated 36, Fig. 1. The sharpness with which the electron beam of the cathode ray tube ID is focused upon the screen I I is determined by the strength of the magnetic field produced by the coil I6, and this in turni depends upon the current owing in the coil. A suitable means such as a potentiometer 38 associated with the power supply 36 is provided to regulate the strength of the current in the-coil I6. The coil I6 may, if desired, be mounted so that its position can be adjusted longitudinally A of the tube II] to further assist in focusing the beam. For simplicity of illustration, however, this adjustment is not shown in the drawing.

Referring now to Fig. 2, the cathode ray tube IIJ is mounted in any suitable fashion on a chassis 36, with the longitudinal axis of the tube II extending in a horizontal direction. In accordance with the invention, the focusing coil I6 is :carried by a holder or supporting member which 4ispivotally mounted on the chassis 36, or alternatively, on a base member supported by the chassis. The holder 3B, as clearly shown in Fig. 3, is U-shaped, having a horizontal bight portion 43 and vertically extending legs 42. A hole 44 in the bight portion 40 receives a screw 46 which pivotally connects the holder 38 to the chassis 36. The focusing coil I6 is bracketed by the legs 42 and is pivotally connected to said legs by bear- I ing studs 48, which are received in holes 49 in the legs 42. The coil I6 is capable of being turned on a horizontal axis extending through the studs ..46 at right angles to the axisof the tube I6, within the limits permitted by the clearance between the coil I6 and the neck 34 of the tube I6.

The pivot 45 allows the holder 38 and the coil I6 to be.v turned as a unit on a vertical axis, within the limits permitted by the clearance between the coil I6 and the neck 34. This enables the electron beam in the tube III to be directed up or down and to the right or left as desired in order to center the image or picture on the screen II.

The delecting coils I2 and I4 are omitted from Fig. 2 so as not to obscure the showing of the invention. These coils usually are mounted adjacent the tube neck 34 in front of the focusing coil I6. The usual chassis components generally designated 5I (tubes, capacitors, coils, power supply) are represented schematically in Fig. 2. The various manual controls of the receiver (other thank the centering control) are represented by the shafts 53 projecting from the front of the chassis 36.

For convenience in manipulating the coil I6, a handle 5G is connected to the coil form and extends rearwardly therefrom through an aperture 52 in the safety panel or shield 54 that customarily is provided at the rear of the receiver.

The handle 59 terminates in a knob 56 which can .be grasped by the operator-,to move the coil I6 on its bearings 48 and pivot 46. IThe requisite .amount of frictionis kafforded at these pivot points so that the coil I6 will retain the position to which it is adjusted. The form of the holder 33 is a matter of choice so long as the focusing 4 coil I6 can be turned about transverse axes perpendicular to the axis of the tube I0 to obtain the desired centering effect.

The centering control described above has the advantage that it is simple to operate and inexpensive to manufacture. It eliminates the separate horizontal and vertical centering controls heretofore employed, and in its operation it has no effect upon the deilection systems 30 and 32, Fig. 1.

The illustrated embodiment is capable of being modified without departing from the principles of the invention set forth above, and it is intended to cover all such modiilcations by the appended claims.

I claim:

1. A centering control for a cathode ray tube comprising an electromagnetic coil adapted to beV positioned on the tube in substantially coaxial relation therewith, a substantially U-shaped supporting member bracketing said coil and pivotally mounted for movement of said member and said coil about a vertical axis, bearing elements connecting said coil to said supporting member for providing pivotal movement of said coil about a horizontal axis, and a single controlling handle connected to said coil for manipulating the same.

2. yA centering control for a cathode ray tube comprising an electromagnetic focussing coil adapted to be positioned on the tube in substantially coaxial relation therewith, a substantially U-shaped supporting member for said coil having a horizontal bight portion and vertically extending legs, bearingl elements connecting said coil to said arms of said supporting member for providing a horizontal bight portion and vertically extendingV legs, bearing elements connecting said magnetic means to said supporting member for providing piovtal movement of said magnetic means about a horizontal axis, a pivotal mounting for said bight Yportion permitting movement of said member and said magnetic means about a vertical axis, and a single controlling handle connected to said magnetic means for moving the same about said horizontal and vertical axes.

4. A centering control for a cathode ray tube comprising an electromagnetic coil adapted to be positioned on the tube in substantially coaxial relation therewith, a holder for said coil, bearing elements connecting said coil to said holder for providing pivotal movement of said coil with respect to said holder about a horizontal axis, a pivotal mounting for said holder permitting movement of said holder and said coil about a. vertical axis, and a single controlling handle connected to said coil for manipulating the same.

5. A centering control for a cathode ray tube including in combination, an electromagnetic f coil adapted to be positioned on the tube in substantially coaxial relation therewith, supporting means for,l said coil permitting pivotal movement thereof about a, vertical axis and a horizontal axis, said supporting means including a holder,

5 6 bearing elementsvconnecting said coil to said UNITED STATES PATENTS holder for pivotal movement about one of said l Number Name Danie axes. and pivotal mounting means for said holder 2 234 720 De Tar Mar 11 1941 permitting pivotal movement of said holder and 2416687 Fry Mai, 4 1947 said coil about the other one of said axes, and a 5 2440403 Jackggrl Apr '27 1948 single controlling handle connected to said coil 2'443973 Asling June'zz 1948 for manipulatingfthe same. 2456399 GARTH J. HEISIG. Gethmann Dec. 14, 1948 f FOREIGN PATENTS REFERENCES CITED l 10 Number Country Date The following references are of record in the 523,439 Great Britain July 15, 1940 le of this patent: 

